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【单选题】
认证权威机构(CA)在签发用户数字证书时,通常使用()来签发数字证书A.
持有的公钥
B.
持有的私钥
C.
用户的私钥
D.
用户的公钥
拍照语音搜题，微信中搜索"皮皮学"使用
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皮皮学刷刷变学霸
举一反三
【单选题】-Hello, may I talk to John please? -( ).
A.
Sorry, he is busy at the moment
B.
No, you can't
C.
Sorry, you can't
D.
I don't know
【单选题】I ______ that John will come to the party. He's busy preparing for an examination.
A.
suspect
B.
doubt
C.
expect
D.
think
【简答题】线偏振光通过四分之一波片,且光的振动面与四分之一波片的光轴方向成30度的角,则出射光为__________。
【单选题】— Is John coming over this weekend? — He should, but he _______ not. He seems to be busy these days.
A.
can
B.
may
C.
must
D.
will
【单选题】John is busy ______ his girlfriend ______ her paper.
A.
help⋯with
B.
to help ⋯with
C.
helping⋯with
D.
to help⋯
【单选题】Mary and John are busy looking for a hotel for their wedding __________
A.
meal
B.
banquet
C.
refreshment
D.
snack
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